The present invention relates to a process for the preparation of formylated phenoxy compounds. More particularly, the present invention relates to a process for converting methyl group in a methylated phenoxy compound selectively into formyl group by liquid phase oxidation with molecular oxygen. Formylated phenoxy compounds are useful as perfumes, medicaments and starting materials for other fine chemicals.
It is publicly known that when a methylated aromatic compound is oxidized with molecular oxygen in liquid phase in the presence of a Redox catalyst, the methyl group of the aromatic compound is converted by oxidation into carboxyl group via formyl group. In this oxidation process, however, the rate of oxidizing formyl group to carboxyl group is much faster than that of oxidizing methyl group to formyl group. Thus, the production of formyl (aldehyde) compounds in a good yield is extremely difficult according to this oxidation process. For this reason, there has not yet been proposed an industrially operable process for preparing formylated aromatic compounds in a good yield by oxidizing methylated aromatic compounds with molecular oxygen.